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        // 1.简单数组去重
        // let arr = [1, 2, 3, 4, 4, 1]
        //     let newArr = arr.reduce((pre, cur) => {
        //         if (!pre.includes(cur)) {
        //             return pre.concat(cur)
        //         } else {
        //             return pre
        //         }
        //     }, [])
        //     console.log(newArr);// [1, 2, 3, 4]
            // 2.数组对象去重
            // let arr = [
            //         { name: 'mom', id: 1 },
            //         { name: 'timo', id: 2 },
            //         { name: 'mom', id: 1 },
            //         { name: 'timo', id: 2 },
            //     ]
            //     let obj = {}
            //     let newArr = arr.reduce((item, next) => {
            //         obj[next.id] ? "" : (obj[next.id] = true && item.push(next));
            //         return item;
            //     }, [])

            //     console.log(newArr);// [{name: 'mom', id:1}, {name: 'timo', id:2}]
                // 3.利用for嵌套for，然后splice去重（ES5中最常用）
                function unique(arr) {
                        for (var i = 0; i < arr.length; i++) {
                            for (var j = i + 1; j < arr.length; j++) {
                                if (arr[i] == arr[j]) {         //第一个等同于第二个，splice方法删除第二个
                                    arr.splice(j, 1);
                                    j--;
                                }
                            }
                        }
                        return arr;
                    }
                    var arr = [1, 1, 'true', 'true', true, true, 15, 15, false, false, undefined, undefined, null, null, NaN, NaN, 'NaN', 0, 0, 'a', 'a', {}, {}];
                    console.log(unique(arr))
    //[1, "true", 15, false, undefined, NaN, NaN, "NaN", "a", {…}, {…}]     //NaN和{}没有去重，两个null直接消失了
    //  4.利用indexOf去重
    function unique(arr) {
            if (!Array.isArray(arr)) {
                console.log('type error!')
                return
            }
            var array = [];
            for (var i = 0; i < arr.length; i++) {
                if (array.indexOf(arr[i]) === -1) {
                    array.push(arr[i])
                }
            }
            return array;
        }
        var arr = [1, 1, 'true', 'true', true, true, 15, 15, false, false, undefined, undefined, null, null, NaN, NaN, 'NaN', 0, 0, 'a', 'a', {}, {}];
        console.log(unique(arr))
   // [1, "true", true, 15, false, undefined, null, NaN, NaN, "NaN", 0, "a", {…}, {…}]  //NaN、{}没有去重
    //   5.利用sort()
    function unique(arr) {
            if (!Array.isArray(arr)) {
                console.log('type error!')
                return;
            }
            arr = arr.sort()
            var arrry = [arr[0]];
            for (var i = 1; i < arr.length; i++) {
                if (arr[i] !== arr[i - 1]) {
                    arrry.push(arr[i]);
                }
            }
            return arrry;
        }
        var arr = [1, 1, 'true', 'true', true, true, 15, 15, false, false, undefined, undefined, null, null, NaN, NaN, 'NaN', 0, 0, 'a', 'a', {}, {}];
        console.log(unique(arr))
// [0, 1, 15, "NaN", NaN, NaN, {…}, {…}, "a", false, null, true, "true", undefined]      //NaN、{}没有去重
// 6.利用includes
    function unique(arr) {
        if (!Array.isArray(arr)) {
            console.log('type error!')
            return
        }
        var array = [];
        for (var i = 0; i < arr.length; i++) {
            if (!array.includes(arr[i])) {//includes 检测数组是否有某个值
                array.push(arr[i]);
            }
        }
        return array
    }
    var arr = [1, 1, 'true', 'true', true, true, 15, 15, false, false, undefined, undefined, null, null, NaN, NaN, 'NaN', 0, 0, 'a', 'a', {}, {}];
    console.log(unique(arr))
    //[1, "true", true, 15, false, undefined, null, NaN, "NaN", 0, "a", {…}, {…}]     //{}没有去重
// 7.set
    function dedupe(array) {
        return Array.from(new Set(array));
    }
    dedupe([1, 1, 2, 3]) //[1,2,3]
    // 8.filter
    function unique(arr) {
            return arr.filter(function (item, index, arr) {
                //当前元素，在原始数组中的第一个索引==当前索引值，否则返回当前元素
                return arr.indexOf(item, 0) === index;
            });
        }
        var arr = [1, 1, 'true', 'true', true, true, 15, 15, false, false, undefined, undefined, null, null, NaN, NaN, 'NaN', 0, 0, 'a', 'a', {}, {}];
        console.log(unique(arr))
//[1, "true", true, 15, false, undefined, null, "NaN", 0, "a", {…}, {…}]
// 9.双层循环，外层循环元素，内层循环时比较值如果有相同的值则跳过，不相同则push进数组
    Array.prototype.distinct = function () {
        var arr = this,
            result = [],
            i,
            j,
            len = arr.length;
        for (i = 0; i < len; i++) {
            for (j = i + 1; j < len; j++) {
                if (arr[i] === arr[j]) {
                    j = ++i;
                }
            }
            result.push(arr[i]);
        }
        return result;
    }
    var arra = [1, 2, 3, 4, 4, 1, 1, 2, 1, 1, 1];
    arra.distinct();    //返回[3,4,2,1]
// 10.利用splice直接在原数组进行操作
    Array.prototype.distinct = function () {
        var arr = this,
            i,
            j,
            len = arr.length;
        for (i = 0; i < len; i++) {
            for (j = i + 1; j < len; j++) {
                if (arr[i] == arr[j]) {
                    arr.splice(j, 1);
                    len--;
                    j--;
                }
            }
        }
        return arr;
    };
    var a = [1, 2, 3, 4, 5, 6, 5, 3, 2, 4, 56, 4, 1, 2, 1, 1, 1, 1, 1, 1,];
    var b = a.distinct();
    console.log(b.toString()); //1,2,3,4,5,6,56
// 11.利用对象的属性不能相同的特点进行去重
    Array.prototype.distinct = function () {
        var arr = this,
            i,
            obj = {},
            result = [],
            len = arr.length;
        for (i = 0; i < arr.length; i++) {
            if (!obj[arr[i]]) { //如果能查找到，证明数组元素重复了
                obj[arr[i]] = 1;
                result.push(arr[i]);
            }
        }
        return result;
    };
    var a = [1, 2, 3, 4, 5, 6, 5, 3, 2, 4, 56, 4, 1, 2, 1, 1, 1, 1, 1, 1,];
    var b = a.distinct();
    console.log(b.toString()); //1,2,3,4,5,6,56
// 12.递归
    Array.prototype.distinct = function () {
        var arr = this,
            len = arr.length;
        arr.sort(function (a, b) {  //对数组进行排序才能方便比较
            return a - b;
        })
        function loop(index) {
            if (index >= 1) {
                if (arr[index] === arr[index - 1]) {
                    arr.splice(index, 1);
                }
                loop(index - 1); //递归loop函数进行去重
            }
        }
        loop(len - 1);
        return arr;
    };
    var a = [1, 2, 3, 4, 5, 6, 5, 3, 2, 4, 56, 4, 1, 2, 1, 1, 1, 1, 1, 1, 56, 45, 56];
    var b = a.distinct();
    console.log(b.toString());  //1,2,3,4,5,6,45,56
// 13.利用indexOf以及forEach
    Array.prototype.distinct = function () {
        var arr = this,
            result = [],
            len = arr.length;
        arr.forEach(function (v, i, arr) {  //这里利用map，filter方法也可以实现
            var bool = arr.indexOf(v, i + 1);  //从传入参数的下一个索引值开始寻找是否存在重复
            if (bool === -1) {
                result.push(v);
            }
        })
        return result;
    };
    var a = [1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 2, 2, 1, 23, 1, 23, 2, 3, 2, 3, 2, 3];
    var b = a.distinct();
    console.log(b.toString()); //1,23,2,3

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